Coil of sheet material wax-tissue laminate in which a lubricant in the wax migrates through the tissue to be sheet material

ABSTRACT

TEXTURING THE SURFACE OF THE SHEET MATERIAL-WAX-TISSUE LAMINATE BY ADDING A LUBRICANT TO THE WAX WHICH IS COATED ON THE SHEET MATERIAL PRIOR TO LAMINAING WITH THE TISSUE, THE LUBRICAWNT, WHICH IS PREFERABLY LIQUID AT ROOM TEMPERATURE, MIGRATES THROUGH THE TISSUE LAYER TO THE SURFACE OF THE LAYER OF SHEET MATERIAL WHICH BECOMES ADJACENT THERETO WHEN THE LAMINATE IS COILED.

Jan. 5, 1971 J. E. KNEPP 3,553,074

COIL OF SHEET MAT AL WAX-TISSUE LAMINATE IN WHICH A LUBRICANT I HE MIGRATES THROUGH THE TISSUE TO SHEET MATERIAL Filed March 13. 1968 2 Sheets-Sheet 1 0 o o 0 o o o 00 Q o oo o 0 o 0 o O 000,

0 080 0 0 o 0 0 0000 WAX INVENTOR. JAMES E. KNEPP aawm m Ar rorney Jan. 5, 1971 J. E. KNEPP 3,553,074

COIL OF SHEET MATERIAL WAX-TISSUE LAMINATE IN WHICH A LUBRICANT IN THE WAX MIGRATES THROUGH THE TISSUE TO BE SHEET MATERIA L Filed March 13, 1968 2 Sheets-Sheet 2 TISSUE UNW/ND INVENTOR. JAMES E. KNEPP A I forney United States Patent O COIL F SHEET MATERIAL WAX-TISSUE LAMI- NATE IN WHICH A LUBRICANT IN THE WAX MIGRATES THROUGH THE TISSUE TO BE SHEET MATERIAL James E. Knepp, Pittsburgh, Pa., assignor t0 Aluminum Company of America, Pittsburgh, Pa., a corporation of Pennsylvania Filed Mar. 13, 1968, Ser. No. 712,818 Int. Cl. B32b 15/12, 31/06 US. Cl. 161-223 6 Claims ABSTRACT OF THE DISCLOSURE Texturing the surface of the sheet material-wax-tissue laminate by adding a lubricant to the wax which is coated on the sheet material prior to laminating with the tissue. The lubricant, which is preferably liquid at room temperature, migrates through the tissue layer to the surface of the layer of sheet material which becomes adjacent thereto when the laminate is coiled.

BACKGROUND OF THE INVENTION This invention relates to a sheet material-wax-tissue laminate. More particularly, it relates to improvement of the lubricant properties of the foil surface of a foil-waxtissue laminate by supply a texturant to the foil surface while the laminate is in coil form.

Sheet material, for example, foil laminate or laminated foil, is used for Wrapping gum, candy, lozenges, cereal, cookies or the like. Heretofore, texturants or lubricants required to permit folding, forming or creasing of lami nates without tearing or scufiing have been applied directly to the sheet material surface, for example, by application from a solvent which is evaporated. Such direct application has proved rather costly and has failed in many instances to provide as effective a lubricated surface as desired, as evidenced by such difficulties oftentimes encountered as breakage of foil during the wrapping operation, as in end tucking, traveling on guide rails or blocking of the foil upon unrolling from coils prior to packaging use. Therefore provision of a foil-wax-tissue laminate having an improved textured surface represents a highly desirable result.

SUMMARY OF THE INVENTION It is an object of this invention to provide a sheet material-wax-tissue laminate which has a sheet material surface of improved lubricant properties when the laminate is wound in coil form. It is a further object of this invention to provide a method of improving the lubricant properties of the sheet material-wax-tissue laminate. A still further object of this invention is to provide a sheet material surface which is resistant to blocking, that is, has a satisfactory degree of slip, when the material is unwound from coil form, and is resistant to scufling and tearing when the foil is used in wrapping mints, candy, cereal or the like. These and other objects will be apparent from the description and claims which follow.

In accordance with this invention, in the manufacture of a sheet material laminate a texturant or lubricant is added to the laminating wax before the wax is applied to the sheet material. The major requirements of the texturant or lubricant according to my invention are (1) that it be compatible with the wax at temperatures above the wax melting point, (2) that it be semi-liquid or liquid, that is, fluid or mobile at room temperature, that is, at about 20-25 C. under ambient conditions, and (3) that it be capable of migrating through the tissue layer to texture the surface of the sheeet material which becomes adjacent to the tissue layer when the laminate is wound in coil form. Useful texturants or lubricants according to my invention include fatty acids and their esters, mineral and vegetable oils, and the like. Such may be used singly or in admixture. One advantage of this use of texturant in the wax is that the wax containing the texturant may be applied to the foil without need for new equipment or costly solvents, for example, by a roller used to apply the wax from a melt contained in a pan or the like before it is laminated with tissue.

When the laminate is wound in coil form and then stored, the texturant, due to its mobility or migrating characteristic at room temperature, is taken up or absorbed by the tissue, which acts much like a wick, and is transferred to the surface of foil adjacent the tissue layer, thereby lubricating it. Concentration of lubricant in wax is controlled such that a suflicient amount migrates through the tissue to provide lubricant properties and machinability to the adjacent coiled foil surface. Concentrations in the range of 0.5 to about 6% by weight, based upon the weight of the wax have proven beneficial with the optimum concentration being about 1.5 to about 2.5%. The lubricant may be dissolved in the wax by heating, preferably to a temperature of about 200 F., the optimum temperature being about -185" F. The Wax containing the lubricant is preferably applied to the foil within about this same temperature range.

The base sheet material of this invention is preferably metal. A metal foil, preferably aluminum, is preferred. By foil we mean any thin sheet metal or metal alloy having a thickness of a few thousandths of an inch or less, usually about 0.006 inch or less, preferably from about 0.0003 to 0.0004 inch. Some of the aluminum foils useful according to this invention are those containing at least about 99% by weight aluminum and up to about 1% by weight silicon and iron or other alloying elements. Copper, manganese, zinc and the like may be also present in such aluminum alloys in amounts up to about 0.1 each. Annealed or dead soft temper aluminum alloys may be laminated according to the invention.

To be useful in containing and transferring texturants according to my invention, the laminating waxes may be of the microcrystalline or parafiin variety, and preferably of strong laminating and heat seal strengths. Microcrystalline wax is preferred, but the preferred microcrystall ne wax may contain 50% or more paraflin. The laminating wax may contain other minor ingredients such as rubber, for example, butyl rubber, a coplymer, for example, ethylene vinyl acetate and ethylene isobutyl acrylates, andresins, for example, terpene or wood resin, or like additives. Preferred amount of wax in coating the foil according to the invention is from about 3 to about 25 lbs. per ream.

For the tissue to have the desired properties for use in the laminate of this invention it should weigh from about 8 to about 20 pounds per 3,000 square feet, be porous and of a sufficiently low density to permit wickage and migration of the texturant or lubricant from the wax and through the tissue to the adjacent foil surface.

In providing the desired lubricant properties to the foil surface according to my invention, the texturant, when transferred from the wax via the tissue to the foil surface when the foil is in coil form, in furnishing the desired anti-blocking or slip properties causes a substantial reduction in coeflicient of friction, viz, from as high as about 1.0 down to a minimum of about 0.15 and down to a range of from about 0.40 to about 0.20, preferably from about 0.35 to about 0.25. The amount of lubricant which reaches the foil surface via the tissue layer upon storage of the foil in coil form is from about 0.0005 mg./in. to about 0.1 mg./in. preferably from about 0.0025 mg./in. to about 0.05 mg./in.

Texturants useful according to the invention in providing the desired lubricant properties, strength and adhesion when transferred to the foil surface from the laminating Wax include lubricants such as butyl stearate, methyl stearate, methyl oleate, methyl myristate, mineral invention in coil form showing the lubricant 2 in the form of a layer or coating on the surface of the foil layer 6 after migration from the wax layer 4 through the tissue layer 8.

FIG. .4 is a schematic representation of one process oil, glyceryl trioleate, glyceryl mono-oleate, acetylated 5 embodiment by 'which my foil laminate containing lubrimonoglycerides, castor oil, dioctyl sebacate, polyethylene cant in the wax may be prepared according to the pressorbitan mono-oleate, silicones, .soybean oil, corn oil, ent invention. In FIG. 4, foil is unwound from coil cottonseed oil, coconut oil, sesame seed oil and the like. 12 and conducted via roll 14 over turning roll 16, which Highly eifective among these are butyl stearate, cotton- 10 applies wax containing lubricant 18 from wax pan 20. seed oil, soybean oil, coconut oil, sesame seed oil and After passing over metering bar 22 the wax coated foil mineral oil. 24 is laminated with tissue 26 from coil 28 by passing The time required for transfer of the lubricant from through the nip formed between rolls 30 and 32 and the laminating wax in which it is applied to the foil surthen wound as laminated foil 34 on coil 36 after passing face through the tissue to the foil surface adjacent the over chill roll 38. tissue layer is from about 1 hour to about 24 hours. The following examples are illustrative of the invention. BRIEF DESCRIPTION OF THE DRAWINGS EXAMPLE I For a more detailed description of the invention reference is made to the accompanying drawings, which illus- Rpresentatlve teXtuTaIltS useful accol'dlflg fills trate a preferred embodiment of the invention. T Q f 1 f )%%3 $303 3 f h Wax P l]l ]i f fi a unnnum 01 o o inc gauge. e 01 DESCRIPTION OF THE PREFERRED was then laminated with tissue and stored in coiled form. EMBODIMENT The textured foil surfaces were then evaluated at various In the drawings: time intervals for coefiicient of friction (COF), both FIG. 1 is a horizontal cross-section of the laminated static and kinetic, textured surface to textured surface, foil of the invention showing the lubricant 2 contained on a conventional moving web-stationary sled apparatus in the Wax layer 4 on the foil layer 6 prior to storage such as described in Bakelite Flexible Packaging Mateand migration through the tissue layer 8. rials Technical Release No. 2, August 1955. The dura- FIG. 2 is a cross-section of the laminated foil of the bility or thumb rub resistance of the textured foil was invention in coil form showing the lubricant 2 contained determined by rubbing the two surfaces against each in the wax layer 4 on the foil layer 6 prior to migration other under moderate thumb pressure with a rub amthrough the tissue layer 8. plitude of approximately two inches. Results are reported FIG. 3 is a cro s-section of the laminated foil of the in T ble 1.

TABLE 1 Coefiieient of friction (static/kinetic), Thumb rub, foil-foil,

foil-foil, moving web average of 2 individuals Percent 10 Texture material by wt. lday 3days 7days lday 3days 7days days None, plainfoilsurlace 1. 0/1.0.9 1.0/1.0.9 1.0/1.0.9 0 0 0 Butylstearate .90/. 66 .82/.65 .75 .40 0 0 0 .70 .49 .30/.60 .32 .42 0 1 1 31 .42 .22/. 27 .20/. 25 3-5 5-7 11 Wesson oil (cottonseed) Acetylated monoglyceride 75% acetylated monoglyceride, 25% dioctyl sebacate-.}

Acetylated monoglyceride 25% butyl stearate plus 75% mineral oil 25% dioctyl sebaeate plus 75% acetylated monoglyceride Wesson oil (cottonseed) ol Glyceryl trioleate EXAMPLE II Textured aluminum foil laminates were prepared substantially as in Example I using .00035 inch foil, 16-lb. wax, 8.5-lb. tissue, and several different lubricants (dissolved in the wax). Evaluations were performed for coefficient of friction and thumb rubs (foil to foil) after aging for various periods, a sufficient amount of lubricant having migrated through the tissue to the adjacent foil surface upon winding of the foil in coils to reduce the coefficlent of friction to the values indicated in Table 2.

TABLE 2 cient of Days friction Thumb after static/ rubs Percent fabrikinetic (foil- Texture material by wt. eating foil-foil foil) None, plain foil surface 44 1.0/1.0.9 0 Butyl stearate 1% 44 23/. 24 4-6 1% 44 25/. 26 34 2 44 22/. 23 4 2 44 22/. 23 34 Wesson oil (cottonseed oil) 2 21 27/. 25 3-4 Wesson oil 2 14 31/. 27 3-4 1 14 31/. 27 3-5 Wessonoil plus butyl stearate (3:1). 2 14 28/. 26 4 Glyceryl trioleate 2 1O 26/. 26 2-3 EXAMPLE III Textured aluminum foil (.00035 inch gauge) laminates were prepared substantially as in Example I using butyl stearate and cottonseed oil as lubricants. Physical properties and functional properties confirming transfer of lubricant from the wax through the tissue to the foil surface are recorded in Table 3.

above the melting point thereof and mobile at room temperature and said lubricant layer being characterized by having resulted from said lubricant having been present in a sufficient amount to migrate from said wax through said tissue and thereby act as a lubricant for the next outwardly adjacent surface of the repeating sheet material layer.

2. The coil of claim 1 wherein the sheet material is aluminum foil, the wax is microcrystalline wax, paraffin wax or a blend of the two, the lubricant is selected from the group consisting of fatty acids, esters of fatty acids and mineral and vegetable oils, and the lubricant comprises from about 0.0005 mg. to about 0.1 mg. per square inch of the next outwardly adjacent surface of the repeating sheet material layer.

3. The coil of claim :1 wherein the sheet material is aluminum foil, the wax is microcrystalline wax, paraffin wax or a blend of the two, the lubricant is selected from the group consisting of fatty acids, esters of fatty acids and mineral and vegetable oils, and the coefficient of friction of the next outwardly adjacent surface of the repeating sheet material layer is from about 0.20 to about 0.40.

4. A method of texturing the surface of a laminated sheet material which comprises coating a sheet material base with wax containing a lubricant which is compatible with the wax at temperatures above the melting point thereof and mobile at room temperature, laminating said sheet material base coated with said wax containing a lubricant with a porous tissue, and winding the resulting laminated sheet material in a coil, said lubricant being present in an amount sufficient upon storage of said coil TABLE 3.FUNCTIONAL PROPERTIES Structure Thumb Coeffiment of friction moving web rubs, Wax N0. (per Texture Foil-foil Foil-stainless strokes ream), weight, Texture lbs. Tissue rug/in. Static Kinetic Static Kinetic Foil-foil Sample No.:

1 Butyl stearate 14. 6 8. 5 001 29 27 26 26 3-5 2 Cotton seed oil 14. 8 8. 5 001 24 23 23 26 4-7 EXAMPLE IV to enable said lubricant to migrate through said tissue Various representative lubricants useful according to the invention were added to laminating wax at 2% concentrations and aluminum foil coated therewith, laminated with tissue and rolled in coils substantially as in Example I, using 14 lb. wax per ream. After varying periods of storage in coil form at ambient temperatures, the foil surfaces were examined and analyzed to test migration and transfer of lubricants and amount of resulting texturing of the foil surfaces. Coefficient of friction and thumb rub tests were performed. Table 4 contains the results of the evaluations.

T AB LE 4 Coefficient of friction, foil to foil,

moving web (static/kinetic) 14 lb./ream wax containing and texture the surface of the sheet material adjacent said tissue with a resultant lowering of the coefficient of friction of said surface.

5. The method of claim 4 wherein the lubricant contained in the wax is from about 0.5 to about 6% by weight of said wax of a substance selected from the group consisting of fatty acids, esters of fatty acids, and mineral and vegetable oils, the wax is rnicrocrystalline wax, paraffin wax or a blend of the two, the sheet material is aluminum foil, the tissue has a Weight of from about 8 to about 20 pounds per 3,000 square feet, and the lubricant is present in the wax in an amount sufiicient to three individuals 2% by weight additive 2 days 5 days 7 days 28 days 2 days 5 days 7 days 28 days Edible soybean oil 34/. 34 33/. 34 26/. 26 1%2 22 2V 3 1V-2 Refined corn oil. .33/. as 29 29 .26/. 26 1 /2-2 2 2-5 232:3 5 Cottonseed cookin 35/. 35 30/. 30 26/. 26 2-3 13-13% 3-4 3-3% Coconut oil 41/. 43 36/. 36 31/. 31 26/. 26 1-2 1} 2% 1%2% 1%-2 A Sesame seed oil 47/. 49 35/. 35 29/. 29 25/. 24 1-2% 2-3 34-23% {+3 4 reduce the coefficient of friction of the surface of the aluminum foil adjacent the tissue to between about 0.20 and 0.40 and is selected from the group consisting of fatty acids, esters of fatty acids, and mineral and vegetable oils.

6. A method of lowering the coefficient of friction of the surface of aluminum foil which comprises dissolving from about 0.5 to about 6% by weight of a lubricant in a microcrystalline or paraffin wax having a weight of from about 3 to about 25 lb./ream at a temperature of from about to about 200 F., said lubricant being compatible with said wax at temperatures above the melting point of the wax and mobile at room temperature, coating aluminum foil at said temperature of from about 160 to about 200 F. with the resulting wax containing said lubricant, laminating said foil with a porous tissue having a weight of from about 8 to about 20 lb./ft. said lubricant being present in an amount sufficient upon storage of the resulting laminate in coil form to migrate differentially from said wax through said porous tissue, and within from about 1 to about 24 hours transferring an amount of said lubricant from said wax through said tissue sufiicient to reduce the coefiicient of friction of foil surface adjacent said laminating tissue by thumb rub test, foil to foil, from substantially no rubs to about 2.0 to 4.0.

References Cited UNITED STATES PATENTS 2,726,979 12/1955 Grant 161223 2,783,161 2/1957 Padgett 106-207 2,847,367 8/1958 Walsh 106270 3,373,915 3/1968 Anderson et a1. 161--223 JOHN T. GOOLKASIAN, Primary Examiner 10 M. E. MCCAMISH, Assistant Examiner US. Cl. X.R. 

